Bones E.J.,Dewberry |
Garrow L.A.,Georgia Institute of Technology |
Sturm T.W.,Georgia Institute of Technology
Journal of Infrastructure Systems | Year: 2017
Scouring around foundations is the most common cause of bridge failures. Scour risk assessment tools allow engineers to better quantify risks associated with existing bridge infrastructure. However, the majority of these tools, including HYRISK, do not incorporate soil property information. This paper develops an approach that associates the critical shear stress of a soil to its Unified Soil Classification System (USCS) soil group classification. This approach is applied to approximately 40 bridges in Georgia using HYRISK and shows how incorporating soil property information changes the expected financial losses associated with a bridge failure. This is important because it enables engineers to use soil property information that is commonly found on boring logs to direct limited maintenance funds to those bridges that are most at risk to scour failure. © 2017 American Society of Civil Engineers.
Ingargiola J.,FEMA Building Science Branch |
Advances in Hurricane Engineering: Learning from Our Past - Proceedings of the 2012 ATC and SEI Conference on Advances in Hurricane Engineering | Year: 2013
The pre-standard for evaluating flood damage-resistant materials was developed to support and clarify NFIP Technical Bulletin (TB) 2 (FEMA 2008). The document addresses structural and aesthetic issues associated with flood damage to building materials but leaves a number of questions unanswered. In an effort to move forward with the pre-standard and address the unanswered questions, FEMA is conducting additional research. This session will include discussions of FEMA efforts to research and evaluate flood damage-resistant materials. The session will begin with the development and progress of the pre-standard, including its intended function under the NFIP and as part of the model building codes. The session will then turn to ongoing research efforts to evaluate the impacts of contaminated floodwaters on building materials and assemblies, including the structural and environmental impacts of certain contaminants on building materials and assemblies. The session will include presentations on both topics followed by facilitated discussions about both projects with participants. This session will discuss the status of FEMA's ongoing efforts in this area and will solicit input on those efforts and any additional efforts participants suggest. Research areas to be discussed include but are not limited to determining a representative floodwater, evaluating the structural impacts of contaminants on building materials and assemblies, evaluating the health impacts of contaminants on building materials and assemblies, and empirical evaluation of the relationship between TB 2 and the pre-Standard. © ASCE and ATC 2013.
Mallin M.A.,University of North Carolina at Wilmington |
McAuliffe J.A.,University of North Carolina at Wilmington |
McIver M.R.,University of North Carolina at Wilmington |
Mayes D.,Wilmington Storm water Services |
Journal of Environmental Quality | Year: 2012
Hewletts Creek, in Wilmington, North Carolina, drains a large suburban watershed and as such is affected by high fecal bacteria loads and periodic algal blooms from nutrient loading. During 2007,a 3.1-ha wetland was constructed to treat stormwater runofffrom a 238-ha watershed within the Hewletts Creek drainage. A rain event sampling program was performed in 2009-2010 to evaluate the efficancy of the wet land in reducing pollutant loads from the storm water runoffpassing through the wet land. During the eight storms sampled, the wet land greatly moderated the hydrograph and retained and/or removed 50 to 75% of the inflowing storm water volume. High removal rates of fecal coliform bacteria were achieved, with an average load reduction of 99% and overall concentration reduction of >90%. Particularly high (>90%) reductions of ammonium and orthophosphate loads also occurred, and lesser but still substantial reductions of total phosphorus (89%) and total suspended solids loads(88%) were achieved. Removal of nitrate was seasonally dependent, with lower removal occurring in cold weather and a high percentage (90%+) of nitrate load removal occurring in the growing season when water temperature exceeded 15°C. Long-term before-and-after sampling in downstream Hewletts Creek proper showed that, after wetland construction, statistically significant average decreases of 43% for nitrate, 72% for ammonium, and 59% for fecal coliform bacteria were realized. Wetland features contributing to the high pollutant control efficiancy included available space for a large wetland, construction of deep forebays, and a dense and diverse aquatic and shoreline plant assemblage. © American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.
Pipelines 2015: Recent Advances in Underground Pipeline Engineering and Construction - Proceedings of the Pipelines 2015 Conference | Year: 2015
Construction is ongoing of a 100-year service life 5.25-mile 42-and 48-inch welded steel pipeline, conveying raw river water from the Potomac River for a 40 MGD water supply system in an urbanizing county in northern Virginia. Ductile iron pipe (DIP) and welded steel pipe (WSP) were specified to create price competition. Transient modeling incorporated material-specific celerity values and showed that vacuum due to surge was more severe than positive surge. Air vacuum relief valves were located at each high point and 4 non-high points where transient surges were predicted. Cathodic protection was designed, consisting of a bonded coating and galvanic anodes. All bids received were for WSP. Lay schedule and shop drawings review assessed alignment, joint types and pulls. Constrained easements prompted reduced radii elbows. The heat shrink sleeve dissipates heat from joint welding after backfill. Daily lay production of 250 feet is planned. The strength of single lap welds was considered. Each weld is to be magnetic particle tested. © 2015 ASCE.
Ingargiola J.,FEMA Building Science Branch |
Forensic Engineering 2012: Gateway to a Better Tomorrow - Proceedings of the 6th Congress on Forensic Engineering | Year: 2013
The National Flood Insurance Program (NFIP) requires that all new, belowbase flood elevation (BFE) construction in the regulatory floodplain be constructed with "materials resistant to flood damage." To provide a quantitative approach to evaluating resistance to flood damage, the Federal Emergency Management Agency (FEMA) Building Science Branch has developed a pre-standard on evaluating flood damage-resistant materials. The pre-standard outlines procedures for identifying the flood damage resistance rating of building construction materials based on mechanical and aesthetic characteristics. The primary users of the standard will be manufacturers who will subject their materials and assemblies to the testing requirements and local building officials who will use the ratings to determine what is allowed in below-BFE construction. In an effort to evaluate the structural and health impacts of contaminated floodwaters on building materials and assemblies, FEMA Building Science is also undertaking a laboratory research task. The task sets out to develop a standard contaminated floodwater for use in evaluation and to evaluate the physical and environmental impacts of that floodwater on building materials and assemblies. © ASCE 2013.
Casey B.,Exponent, Inc. |
Germaine J.T.,Massachusetts Institute of Technology |
Abdulhadi N.O.,Arab Center for Engineering Studies |
Kontopoulos N.S.,Fugro |
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2016
A reliable estimate of secant undrained Young's modulus (Eu) is necessary to quantify the undrained settlement of structures underlain by fine-grained soils. A large number of CK0UC triaxial tests have been carried out on eight resedimented clays to establish the effects of soil composition, applied shear stress, overconsolidation, and vertical consolidation stress on the magnitude of Eu. These tests were performed at effective stresses ranging from 0.02 to 100 MPa. Low plasticity soils tend to have a higher Eu compared with high plasticity soils. The effect of composition diminishes as the applied shear stress increases. Overconsolidated (OC) soil has a higher undrained modulus than normally consolidated (NC) soil, though a change in the overconsolidation ratio of OC soil does not have a significant effect on Eu. Regression analyses performed on the experimental data define relationships for Eu as a function of stress level for both NC and OC soil. © 2015 American Society of Civil Engineers.
Said H.,Santa Clara University |
Practice Periodical on Structural Design and Construction | Year: 2014
Because of the negative environmental and social impacts of built environment activities, several rating systems were developed in the last two decades to help professionals evaluate the sustainability of their design and construction decisions. A recent study revealed that industry leaders reported the shortcomings of these rating systems to provide accurate valuation of the return on their green investments. The study suggested the development of new evaluation processes that consider the triple-bottom-line (TBL) aspects (social, environmental, and financial) of project sustainability in a more holistic approach. Accordingly, this paper identifies the gaps between current practices and envisioned TBL-based practices through the following three main tasks: (1) surveying industry professionals to identify their current practices and required skills of sustainable design and construction; (2) surveying a sample of national academic engineering programs to identify current offerings of required sustainability courses; and (3) applying needs assessment to highlight the gaps and needed actions for achieving envisioned practices. It is proposed to implement a top-bottom action plan to develop new TBL-based processes that better inform sustainable/green investors and owners. © 2014 American Society of Civil Engineers.
Wang L.-S.,State University of New York at Stony Brook |
Ma P.,State University of New York at Stony Brook |
Hu E.,State University of New York at Stony Brook |
Giza-Sisson D.,Dewberry |
And 2 more authors.
Energy and Buildings | Year: 2014
It is common knowledge that buildings should be constructed with good envelopes and sufficient masses. However, U.S. building codes make no provision for a building's thermal mass. This may result from that the conventional heat balance design - which assumes constant indoor air temperature, any heat imbalance resulting from corresponding envelope heat loss or gain and internal heat gain is accounted for by HVAC equipment - aims for HVAC selection, not for determining required building thermal qualities. We propose the concept of building thermal autonomy and a two-step process assumption-based design method. Thermal autonomy is a building's capability of keeping its indoor temperature sans HVAC equipment within a prescribed temperature range. The first step of the process assumption-based design method aims for the determination of building thermal qualities for a thermally autonomous building. Our finding shows that optimum slab thickness for a building's ceilings and floors is 25-cm and recommends 10-cm thick concrete slabs for its envelope walls. More interesting is the finding that climate-specific factor of diurnal temperature amplitude should be taken into consideration in the envelope design: a maximum WWR (Window-to-Wall Ratio) is given as a function of diurnal temperature amplitude. © 2014 Elsevier B.V.
Association of State Dam Safety Officials - Dam Safety 2011 | Year: 2011
This study shows that under the PMF conditions the inflow to the reservoir must be considered in any empirical or simplified equation for dam break peak outflow. The assumption of a full reservoir with no dam inflow may result in underestimating the peak flow. An existing peak flow equation was revised to directly include the impact of the PMF inflow in the dam break peak discharge. The resulting equation provides a simple way to conservatively estimate the dam break peak discharge under PMF conditions.
PubMed | Environmental Quality Management, Colorado State University, University of Toronto, U.S. Geological Survey and 3 more.
Type: Journal Article | Journal: Integrated environmental assessment and management | Year: 2016
Chemical contamination has impaired ecosystems, reducing biodiversity and the provisioning of functions and services. This has spurred a movement to restore contaminated ecosystems and develop and implement national and international regulations that require it. Nevertheless, ecological restoration remains a young and rapidly growing discipline and its intersection with toxicology is even more nascent and underdeveloped. Consequently, we provide guidance to scientists and practitioners on when, where, and how to restore contaminated ecosystems. Although restoration has many benefits, it also can be expensive, and in many cases systems can recover without human intervention. Hence, the first question we address is: When should we restore contaminated ecosystems? Second, we provide suggestions on what to restore-biodiversity, functions, services, all 3, or something else--and where to restore given expected changes to habitats driven by global climate change. Finally, we provide guidance on how to restore contaminated ecosystems. To do this, we analyze critical aspects of the literature dealing with the ecology of restoring contaminated ecosystems. Additionally, we review approaches for translating the science of restoration to on-the-ground actions, which includes discussions of market incentives and the finances of restoration, stakeholder outreach and governance models for ecosystem restoration, and working with contractors to implement restoration plans. By explicitly considering the mechanisms and strategies that maximize the success of the restoration of contaminated sites, we hope that our synthesis serves to increase and improve collaborations between restoration ecologists and ecotoxicologists and set a roadmap for the restoration of contaminated ecosystems.